package com.zbkj.admin.boot.redisson.ratelimiter;

import lombok.RequiredArgsConstructor;
import net.dreamlu.mica.core.spel.MicaExpressionEvaluator;
import net.dreamlu.mica.core.utils.CharPool;
import net.dreamlu.mica.core.utils.StringUtil;
import org.aspectj.lang.ProceedingJoinPoint;
import org.aspectj.lang.annotation.Around;
import org.aspectj.lang.annotation.Aspect;
import org.aspectj.lang.reflect.MethodSignature;
import org.springframework.beans.BeansException;
import org.springframework.context.ApplicationContext;
import org.springframework.context.ApplicationContextAware;
import org.springframework.context.expression.AnnotatedElementKey;
import org.springframework.expression.EvaluationContext;
import org.springframework.lang.NonNull;
import org.springframework.util.Assert;

import java.lang.reflect.Method;
import java.util.concurrent.TimeUnit;

/**
 * redis 限流
 *
 * @author L.cm
 */
@Aspect
@RequiredArgsConstructor
public class RedisRateLimiterAspect implements ApplicationContextAware {
    /**
     * 表达式处理
     */
    private final MicaExpressionEvaluator evaluator = new MicaExpressionEvaluator();
    /**
     * redis 限流服务
     */
    private final RedisRateLimiterClient rateLimiterClient;
    private ApplicationContext applicationContext;

    /**
     * AOP 环切 注解 @RateLimiter
     */
    @Around("@annotation(limiter)")
    public Object aroundRateLimiter(ProceedingJoinPoint point, RateLimiter limiter) {
        String limitKey = limiter.value();
        Assert.hasText(limitKey, "@RateLimiter value must have length; it must not be null or empty");
        // el 表达式
        String limitParam = limiter.param();
        // 表达式不为空
        String rateKey;
        if (StringUtil.isNotBlank(limitParam)) {
            String evalAsText = evalLimitParam(point, limitParam);
            rateKey = limitKey + CharPool.COLON + evalAsText;
        } else {
            rateKey = limitKey;
        }
        long max = limiter.max();
        long ttl = limiter.ttl();
        TimeUnit timeUnit = limiter.timeUnit();
        return rateLimiterClient.allow(rateKey, max, ttl, timeUnit, limiter.msg(), point::proceed);
    }

    /**
     * 计算参数表达式
     *
     * @param point      ProceedingJoinPoint
     * @param limitParam limitParam
     * @return 结果
     */
    private String evalLimitParam(ProceedingJoinPoint point, String limitParam) {
        MethodSignature ms = (MethodSignature) point.getSignature();
        Method method = ms.getMethod();
        Object[] args = point.getArgs();
        Object target = point.getTarget();
        Class<?> targetClass = target.getClass();
        EvaluationContext context = evaluator.createContext(method, args, target, targetClass, applicationContext);
        AnnotatedElementKey elementKey = new AnnotatedElementKey(method, targetClass);
        return evaluator.evalAsText(limitParam, elementKey, context);
    }

    @Override
    public void setApplicationContext(@NonNull ApplicationContext applicationContext) throws BeansException {
        this.applicationContext = applicationContext;
    }
}
